SBIR-STTR Award

Conventional watering uses hose or boom irrigation systems to apply excess water to ensure complete coverage of the entire crop to the point of full saturation of the root medium. This method is costly in terms of water and nutrients. Water falls outside the area of the pots and is lost to the environment. Excess water may leach up to 75% of the fertilizer from potted plants. It may be necessary to recirculate wastewater when excess water is applied in plant production, The risk of propagation of disease from splashing and other mechanisms causes growers to adopt a preventative program of pesticide applications that increase production cost as well as potential exposure to pesticides of the employees and customers. Our system reduces the runoff of water, fertilizer, and pesticides, that are an integral part of conventional watering systems, and that are a potential risk to the quality of the environment in proximity to the greenhouse operation. OBJECTIVES: Objective one. To refine the timing and duration of water delivery and drainage for a partial saturation ebb and flood system to achieve any desired fraction of water saturation of the root medium, for a variety of ornamental plants and pot sizes. Objective two. To evaluate growth and development of ornamental plants grown using partial saturation ebb and flood, and to compare these measurements to those for plants grown with conventional watering. To relate physical properties and nutrient status of the root medium to the growth of plants. APPROACH: Geremia Greenhouse has developed the plumbing for water delivery and return systems for ebb and flood watering of short duration. This water delivery and control method will be expanded to a bench watering system on a commercial scale of 100 square feet. Plumbing and wiring of solenoid valves will be modified such that each unit can be controlled independently, in terms of timing and duration of watering. Water gauges will be installed in each bench to accurately the volume of water supplied and drained during each watering event. These irrigation units will be used to vary the timing and duration of watering to determine the parameters required to achieve 40%, 60% 80% or 100% saturation of the root medium. In this and all other studies the pots will be filled with a root medium primarily consisting of peat and vermiculite. Another series of tests will use pots containing plants with established roots, namely, geranium, chrysanthemum and poinsettia in 4-, 6-, and 10-inch pots, respectively. Pots will be set out at normal spacing to completely cover the experimental benches. The experiments described above will be repeated with a full bench of potted plants, to determine how the plant material and population of pots affects the uniformity of uptake of water. We will grow crops of plants to marketable size using PSEFW, and compare their growth to that in trickle irrigation systems and conventional ebb and flood with complete saturation of the root medium. Development and flowering times will be measured. Three independent watering systems of each type will be set up for each treatment comparison. All watering systems will be compared at the same time and in the same greenhouse. Geranium, chrysanthemum, and poinsettia will be grown in 4-, 6-, and 10-inch pots, respectively, in separate experiments. The partial saturation ebb and flood system will be set to give a fixed level of 80% saturation throughout the study. Plants watered by this method will be compared to those grown under 100% saturation throughout development, and to those with drip irrigation to 20% over-watering. Dry matter and nutrient status will be measured for a sub-sample of plants at flowering. The physical properties of the root medium will be measured for pots subject to the different watering methods. Early in the growing cycle and at the midpoint in growth, and at flowering, a sub-sample of potted plants will be chosen to determine the physical properties of the root medium. The physical properties of the root medium and the gradient in water, pH, nutrients and plant roots will be determined as a function of height in the pot

Sub irrigation combats the waste of water and fertilizer in traditional overhead watering systems used in greenhouses for production of potted ornamental plants. However, current ebb and flow watering systems achieve nearly complete saturation of the root medium for each watering cycle. There is no ability to restrict the water provided to the plants. This may decrease plant quality and facilitate spread of disease. Geremia Greenhouse has developed a method to achieve partial saturation with ebb and flow watering of the root medium for production of potted ornamental plants. The water or fertilizer solution is delivered and removed rapidly, resulting in less water absorbed by the pots, and little leaked back out of the pots. This research will determine the benefits of partial saturation ebb and flow watering when applied on flooded floors, in terms of improved quality and shelf life of potted flowering plants, and reduced spread of disease. In-line filtration and sterilization methods will be tested to prevent spread of disease. Once the system is optimized, Geremia Greenhouse will apply this method on a scale of several acres. The improved plant quality and shelf life will benefit growers and consumers, and this watering system will protect natural resources and the environment.